I finally caught this on cable a while back. The film had an interesting life on teh interwebz, first inciting hysteria among the Ain't-It-Cool nerd crowd ("Bruce Campbell in a film about Elvis fighting a mummy? Sweet!") before moving on to disappointment and a general consensus that the film was a bit of a let down.
Curiously the film is one of those movies that I feel respect for more than outright affection. Campbell plays an Elvis who has gone to seed, aged into senescence and is packed off to a rest home to die. He's got a cancerous tumor on his "pecker" but the nursing home staff have decided against treatment or even informing their patient about his condition, figuring that he'll die of old age long before the cancer gets him. There's a mummy, but the heart of the film isn't Campbell's eventual (anti-)climatic confrontation with the monster. Instead it lies in a scene where a blond piece of fluff comes by to dispose of her father's belongings after he's died and flings his WWII medals into the trash.
It's been a long time since I read the Joe Lansdale short story the movie's based on and I can't remember if that scene is from the original source material, but I like to think it is. And I like to think that the writer/directory, Don Coscarelli of "Phantasm" fame, chose to keep it in the movie even if the result was a film that was too low key and melancholy to be a hit with the fan boys. The movie's got some issues with pacing and it doesn't quite work, but at least I get the impression that everybody involved with it got to keep their self-respect.